1. Technical Field
The disclosures herein relate generally to conduits which are useful as medical devices applicable to neuroregeneration; more particularly, to implantable nerve regeneration conduits for facilitating the regrowth or repair of nervous tissues.
2. Related Art
Nerve injuries are common in clinical practice. According to statistics, more than 90,000 people are affected by nerve injuries every year. While the central nervous system (CNS) is, for the most part, incapable of self-repair and regeneration, the peripheral nervous system (PNS) has an intrinsic ability for repair and regeneration. Studies on the recovery of PNS functionality after injury have become a rapidly growing field dedicated to the searching of suitable ways for facilitating neuroregeneration.
Various approaches have been developed in an attempt to regenerate injured nerves. One such technique involves the actual suturing of the proximal and distal ends of the severed nerve. When a nerve defect of gap is longer, implantation of a graft is often necessary to bridge the stumps for promoting nerve regeneration. Currently, the most widely used material to bridge a peripheral nerve defect is the autologous nerve, e.g., nerve tissue obtained from a second operative site of a patient. However, this treatment raises the possibility of function loss at the donor site, formation of potential painful neuromas, structural differences between donor and recipient grafts, and difficulty in finding a suitable donor site of transplant in patients with diabetic and other chronic diseases, not to mention a potential shortage of graft material where extensive repairs are required.
Therefore, it would be desirable to have an alternative nerve graft material that not only fulfills the requirements, but also overcomes many of the shortcomings, of a nerve autograft. A promising alternative for nerve regeneration which avoids the above-mentioned problems is an artificial graft. In fact, many types of biomaterials, natural or synthetic, have been used to make tubes or conduits for guiding peripheral nerve regeneration.
Conventionally, nerve conduits are made of silicone rubber due to its chemical stability and elastic properties. However, because silicone tubes are non-biodegradable and non-porous, conduits made of silicone rubber often lead to long term complications including fibrosis and chronic nerve compression in clinical applications, and a second surgery is often necessary for removal of the tube or conduit. Accordingly, nerve guide conduits fabricated from biodegradable polymers are preferred over non-biodegradable polymers due to the obvious advantage of eliminating the second surgery to remove the conduits.
The purpose of a resorbable nerve conduit is to provide unperturbed environment for nerve regeneration in short term and to degrade after nerve reconstruction with little tissue reaction. Although a variety of resorbable nerve conduits have been developed, the results thus far are still not satisfactory, and the search for a better conduit is ever ongoing. Therefore, there is a need for an improved nerve conduit for facilitating the regrowth, repair, or regeneration of nervous tissues.